Written and designed by Roy Shepherd. Special
thanks to my wonderful wife
Lucinda Shepherd, friend Robert Randell and various experts for their
support.

Conserving Prehistoric Evidence

Left: A bone block
appearing to contain ichthyosaur bones and teeth has been polished rather
than more respectfully prepared. The result is minimally
informative and parts of the specimen have been lost. Better results can be
achieved using an air-pen or an acid bath.Right: A conscientiously hand-prepared ichthyosaur skeleton
from Lyme Regis (Dorset), displaying all available anatomical information and retaining the
entire specimen. Manual preparation in the way requires significantly more
hours of work, however the benefits are clear to see.

Introduction

In the following article attention is drawn to the benefits of conserving
prehistoric evidence and how inappropriate collection, preparation, visual alteration
and storage can
have a detrimental effect. The aim is to highlight the features that
contribute to a fossil's scientific value and promote the benefits of
conserving these. Examples are provided to illustrate the actions
that can result in a loss of evidence and therefore scientific value. The article is intended to share some
of the personal insights and experience that Robert and I have gained over the years,
and hopefully encourage best practice.

Fossil conservation is often a controversial subject and one that
involves aspects of personal preference, i.e. what one person
considers beneficial another considers detrimental. Similarly, what
an enthusiast considers good practice typically changes with time,
increased knowledge & understanding and access to specialist
equipment. There are no strict guidelines for fossil conservation -
individuals are largely free to decide how they collect and conserve
specimens, and where they reside, e.g. a museum, private display,
attic, etc. We too have experienced the same change in views and
share the pain of some early prep jobs - below are some examples
that are best not repeated.

Left: A Clypeus ploti
echinoid from Woodeaton Quarry (Oxfordshire). Although the matrix
(surrounding rock) has been carefully reduced to expose the specimen,
a surface lacquer has then been applied in an attempt to enhance the aesthetics. Such practice obscures important surface details and generally results is a
misleading appearance that lessens the specimen's appeal. Good
scientific practice would have been to leave the surface in a natural / unaltered state.Right: An Androgynoceras
ammonite from Seatown
(Dorset) partially exposed at the surface of a
nodule. To reveal an ammonite such as this, an air-pen
provides
the necessary power and precision for an effective outcome. Unfortunately however, at the time of preparing this particular
specimen such tools weren't easily
accessible. Consequently it was thought possible to tackle the preparation with
a sharp blade - the result was a damaged specimen that
was ultimately discarded.

Left: A Temnocidaris sceptrifera
echinoid residing at The Booth Museum in Brighton. Although a
beautiful and near complete specimen, the preparation has
removed too much chalk matrix resulting in an overly fragile
specimen. A more robust plaster backing is now planned to provide stability of the specimen.Right: An articulated Leptotrachelus chalk fish from
Seaford Head
(East Sussex) is mistaken for a Terebella (a crustacean
burrow lined with fish scales/bones)
and decapitated during extraction. Only after the portion containing the skull had been removed was the
error recognised. A little more patience and
consideration
may have
allowed time to recognise the specimen, thus avoiding the ensuing damage. The two
halves have been reunited, but the
damage can never be undone;
however, careful reconstruction and application of a chalk-based
'filler' will effectively disguise much of the visible damage.

The basic conservation issues usually relate to aesthetics, commerciality,
knowledge and skills / experience. Both amateurs and commercial collectors are prone to
collecting and preparing specimens in ways that emphasise their aesthetic
qualities. This is not necessarily damaging to a specimen, but often can be.
Examples include rare articulated vertebrates being
collected as small pieces, e.g. collecting only the heads because the body is
preserved in a 'less impressive' state or difficult to retrieve. This overlaps with commerciality – often decisions on
how/what to collect and how to prepare are based on cost effectiveness. For
example a fragile chalk fish might require several weeks of prep, but this
isn't commercially viable; an ammonite might not ‘pop’ well, so easier to
slice it; a crushed outer whorl of an ammonite is unsightly, so remove it; the matrix
around an echinoid might be tough, so crank-up the air abrasive, stripping
the surface detail in the process! Also, the lucky beginner may discover
a specimen they simply don't know how to collect and conserve –
stories of bits being hacked off skeletons because they
were ‘too
big to collect whole’.

Below we discuss the fundamental concept of treating fossils and
fossil locations with respect and understanding how and when to
take appropriate action. Attention is drawn to knowing your limits - some finds warrant
professional preparation or simply waiting until you're
better experienced or equipped. Good preparation requires an
understanding of how the fossil material and matrix behaves, the
different techniques and equipment needed, and also an understanding of
the anatomy of the specimen and its general scientific value.
Someone who collects regularly from a particular rock formation can
quickly acquire this knowledge and experience, and even become a
recognised expert. There are many places
a new collector
can seek advice on the scientific value of specimens and how
they're best conserved, these include local geology groups, museums,
discussion forums, commercial
preparators and the Discovering Fossils team. We're always happy to
answer questions, offer advice and put people in touch with the
relevant professionals.

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Prehistoric evidence

For many people their first appreciation of fossils was for their
aesthetics, perhaps as a child stood gazing up at a dinosaur
skeleton in a museum, or admiring an ammonite through a shop window.
It's easy to understand the appeal of a well presented fossil - we
appreciate the skilful work undertaken to expose it and it
helps us imagine how the organism once lived. Of course there's
nothing wrong with this, we should admire fossils in this way, but
we should also consider the science too. Similarly, we should show
respect for the ancient and scarce in the same way we would a Roman
mosaic or Renaissance painting for example.

The science of palaeontology involves the interpretation of
prehistoric evidence and to be of greatest value it needs
to be as unaltered as possible. Manual preparation should seek to
reveal and conserve the evidence available, with aesthetic
preferences confined to the presentation of the surrounding rock
(matrix), in this way the conservation of the evidence
always takes priority.

Left: This Offaster from
Peacehaven
(East Sussex) has
been conserved with the chalk matrix in order to
capture associated information about the prehistoric
seabed. Without the matrix it's often impossible to tell what formation
the specimen have come
from, where they came from and even what age they are.Right: A cupedid beetle (12mm) from Smokejacks Brickworks
(Surrey). The head remains
obscured within the matrix until a means of revealing it
without
risking the specimen can be found. It's good practice to
resist the temptation to prepare/expose fossils in the field, better
to
undertake preparation at home.

Left: Despite its beach-worn surface this
nautiloid from Osmington Mills
(Dorset) comprises
a large portion of the original specimen and we would argue is
best
conserved as found. The aesthetics are perhaps unsightly and common
practice would be destructive modification to improve its appearance
/ commercial value.Right: A display of chalk fossils in the Booth Museum in Brighton.
The specimens have been carefully prepared and conserved in their
natural state.

Left:
An air-abrasive tool being used to expose the surface of this echinoid
from a Lewes (East Sussex) quarry. The matrix is retained for environmental context.Right: A close-up of the
air-abraded surface of the echinoid reveals
the often absent spines which covered the specimen in life. A more
aggressive
preparation
technique, e.g. a pen knife, would have removed these in an
instant.

Left: The outer
whorl of this ammonite from Osmington Mills (Dorset) is worn and
some might say 'unsightly', arguably though this feature is best
conserved.Right: This nodule from
Seatown
(Dorset)
contains Androgynoceras ammonites and ichthyosaur
vertebra, and we would argue best conserved together
as an association.

Left: A
Goniopholis crocodile tooth and surrounding matrix from
Durlston
Bay (Dorset), the latter contains plant debris which can help confirm the
environmental
setting and the age - in this instance an ancient lagoonal setting dating
from the Early Cretaceous Epoch, approximately 140 million years ago.Right: A Clypeus ploti echinoid from
Woodeaton quarry (Oxfordshire) partly obscured beneath a broken
bivalve shell. Like the examples above the bivalve adds
environmental, depositional and ecological context to the echinoid and vice versa.

Fossils not only provide evidence of the organism itself but often the
taphonomic processes during the interval between death and long-term burial, e.g. scavenging and encrustation. For example, a heavily encrusted specimen
reveals the specimen lay exposed on the seabed for sufficient time that
marine organisms colonised its surface. Furthermore, it also reveals the
seafloor was oxygenated and provides clues to the specimen's orientation. This added contextual information enriches our
interpretation of the prehistoric environment in which the specimen once
lived. When preparing a specimen it's worth conserving
any surface features for the environmental and/or biological context they
add.

Left: This Pectinatites ammonite from
Kimmeridge (Dorset) is
partly obscured by pyritised oyster shells. The presence of the oysters
indicates the ammonite
lay exposed on the seabed for a sufficient time for them to colonise
its surface (possibly the underside). The oysters are part of this specimen's
history.Right: Divers investigate a 'recent' shipwreck. The surface of the
wreck is heavily encrusted providing evidence of how long the ship has lain
on the seabed.
Like the fossil examples discussed the shipwreck encrustations are an equally important
feature and add to our understanding of the past.

The partial ammonite shown below could easily be overlooked, however
this particular specimen features good examples of marine encrusters that
colonised the inner surface of the shell. From this we can deduce that soon after the ammonite's death
its shell sank to the seafloor where it acted as an underwater cave providing shelter for a variety of
organisms, in particular tube-worms. Comparisons with present-day encrusters
allow us to draw information concerning oxygen and temperature conditions
on the seafloor. We can also ascertain that sediment accumulation took place
slowly i.e. the shell lay exposed for sufficient time for encrusters to
colonise it. The fact that the ammonite's aragonite shell dissolved, whilst the worm tubes are preserved (as calcite) on the surface of the
mould also informs us about the seabed chemistry.

Left: A chalk boulder from
Beachy Head
(East Sussex) containing the partial internal mould of a large
ammonite shell - the shell has
naturally dissolved.Right: A close-up reveals the internal shell
surface (preserved at the surface of the boulder) was colonised by
tube worms, their spiral shells clearly visible.

Left: The skull of a
Leptotrachelus fish, found within the Plenus Marls at
Beachy Head (East Sussex).
Note the echinoid spine retained for biological context.Right: An ammonite obscured by pyritised oyster
shells, found loose on the beach at
Kimmeridge (Dorset). The oysters add to the
interest of this specimen.

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Collection practices

The following section discusses the collection practices that
can help conserve prehistoric evidence and conversely the actions that can result
in its loss. Often, decisions at this initial
stage have the greatest impact on the lasting scientific value of
the specimen i.e. only what's collected can be prepared and
interpreted. The focus here is on the value of retaining the matrix
during extraction and also the benefits of collecting the
specimen whole, or if broken, retrieving all the
pieces available. For an introduction to basic fossil collecting
practices please refer to our Fossil
Hunting Guide - here you'll find more information about
legalities, extraction, transportation and recording key information
in particular.

Retaining matrix: Matrix is the general term used
to describe the associated rock that surrounds a fossil, and its retention has a number of benefits.
First and foremost the matrix helps conserve the fossil by acting as a
protective shield, without which it may be vulnerable to damage
during transportation and storage/display. It's worth keeping in mind the
balance between removing sufficient matrix to expose the fossil and
the added risk exposure creates. Retaining a generous amount of matrix
during extraction is recommended especially around the most fragile parts. The
retained matrix can also be shaped to provide a stable base to
display the specimen after the detailed work is complete.

Left: In order to safely extract this fish
vertebra from a chalk boulder at
Beachy Head (East Sussex) a hand saw is used to make a series of cuts in the
matrix.
Water is added to assist the cutting action of the saw - it prevents the sediment
clogging the cutting line, reducing friction and therefore the
likelihood of the saw
jarring and shattering the specimen. It's good practice to carry
a small bottle
that can be topped-up with seawater or preferably fresh if
available.Right: A chisel is then used to remove the excess
matrix, leaving the vertebra and a rectangular piece of matrix in
the centre which can be safely extracted.

Left: The pieces of matrix surrounding this
Liparoceras ammonite from
Seatown (Dorset) have been recovered in
order to reattach any
shell fragments.Right: An ammonite anaptychus ('closing
hatch') in situ near
Kimmeridge (Dorset). Retaining the matrix
during extraction helps provide long-term stability
to the specimen.

Matrix also provides useful information about the environmental
processes and organisms present at the time of burial.
For example, the chalk matrix associated with the fish vertebra
(shown above) reflects a marine sediment deposited far from land, largely free of
terrestrial sediment that would otherwise have coloured it. The
chalk matrix also contains additional fossil material,
including fragments of bivalve shell, bryozoan skeletons and
microscopic foraminifer and nannofossils that can help date
the specimen in the event of the recorded information being
misplaced. The matrix may also preserve sedimentary structures
relating to how the specimen came to be preserved, e.g. rapid
burial - an often poorly understood process.

Retrieving all of the specimen: An association of prehistoric evidence is always of greatest value when
collected whole, or when all the pieces are available together. As a
general guide there are few instances where retrieving the specimen
in pieces (unless broken already) is the best strategy; far better
to retrieve the specimen complete. Where a specimen has broken, it's
typically best to retrieve all the matrix blocks so it can be
seamlessly reassembled.

In the example below-left, a Nymphaster starfish is found exposed at
the surface of the Plenus Marls at
Beachy Head (East Sussex). The complicated position of the
specimen and existing faults passing through it, mean a dissection
is unavoidable. Over the space of several hours the individual
pieces were carefully removed, being mindful to collect any matrix
that may contain parts of the starfish. At home the individual
pieces were soaked in fresh water to remove the salt, then
reassembled and a plaster backing added to provide extra
support. The result of collecting all the pieces is soon evident as
the full extent of the fossil appears during further
preparation (see photo below-right).

Left: A Nymphaster starfish exposed at the
surface of the Lower Chalk, Plenus Marls at Beachy Head (East Sussex). Note the
numberous natural cracks passing
through and around the specimen. Dissecting the specimen along these
existing cracks in unavoidable in this instance.Right: Having been reassembled and a plaster
backing added (visible at the top of the photo), the next step to
expose the starfish can begin. The photo shows
the early results, with two of the creature's arms visible at the
top and right of the photo. Further preparation will reveal if more
of the specimen is present.

Often however, specimens may suffer intentional dissection, perhaps because part of the specimen
was out of reach or obstructed making a thorough
extraction more difficult or time consuming. In a worst-case
scenario only the parts of the fossil perceived as having greatest value
are retrieved, leaving the remaining pieces behind. Often the
problem results from having inadequate tools/experience or extracting the specimen
too hastily. In the example below dissection resulted
from a failure to recognise the significance of the find until it's too
late.

Left: A large septarian nodule on the beach at
Charmouth
(Dorset) containing
the complete and articulated remains of a large and scarce Early Jurassic
fish
(note goggles for scale).
A commercial collector broke up the boulder but
rejected the specimen not considering it to be commercially viable.
One of the
Discovering
Fossils team
reassembled the pieces and then returned to the
nearby conservation centre for help retrieving the specimen from the beach. During
those few minutes a local collector took the lazy option and broke off the head and fins, inflicting irreparable damage to the specimen.
Right: The outline suggests how the specimen would have
looked
if preparation had taken place and shows what a significant specimen it was.

In the following example a rare articulated ichthyosaur
paddle was unknowingly broken apart by an inexperienced collector and
rejected. Despite the devastation the significance of the various
pieces was recognised by a passing father and son who
conscientiously gathered the pieces so they could be
reconstructed. After many hours of painstaking work the
resulting outcome is plain to see - the arrangement of the bones
depicts their life positions and provides a fascinating
insight to how these creatures propelled themselves through the
water.

Left: A broken septarian nodule found on Monmouth Beach at
Lyme Regis (Dorset) containing
the articulated bones of an ichthyosaur paddle - seen here as dark
areas against the grey limestone. The specimen was presumably
smashed by an inexperienced visitor who subsequently rejected the
specimen. Fortunately the
pieces were rediscovered by a father and son who recognised their
significance and gathered the fragments in order than they could be
reassembled.Right: After many hours of painstaking
reconstruction, using only hand tools, the splendour of the
discovery is plain to see. The humerus can be
seen at the far left of the specimen, connected to which are many
articulated phalanges that make up the paddle.

The ichthyosaur example (above-left) graphically illustrates the
danger resulting from a lack of subject familiarity, and perhaps
more importantly knowing when to halt hammering and reassess the
situation or seek advice. It's often the case that the significance
of a find only becomes apparent part way into the extraction i.e.
when it's evident there's a degree of order to the bones for
example.

Perhaps the most high-profile example of a dissection in recent
years involved one of the principle dinosaur trackways at Ardley
quarry (Oxfordshire) prior to the site's protection in
2010. Following the discovery of the trackways in 1997 Ardley has
attracted international interest, partly due to the high volume and
length of trackways exposed, but also because one in particular
(thought to belong to a Megalosaurus) revealed how the
dinosaur accelerated from walking to running. Perhaps this was
evidence that the dinosaur has been stalking its prey prior to
launching a high speed attack? This unique trackway began with a
stride length of 2.7 metres while walking at 7 km/h, increasing to
5.5 metres when running at 30 km/h. Furthermore
the footprints revealed that whilst walking the dinosaur
splayed its feet out widely with the toes pointing inwards, whereas
when it ran it tucked its feet beneath its body.

Although the early conservation of the trackway was sufficient to allow
time for numerous visits, studies, and a plaster cast to be taken, the
site eventually suffered damage from quarry vehicles and weathering. In an
effort to conserve a small number of the remaining footprints, the trackway
was dissected and the removed pieces placed on display at the Oxfordshire
Museum. Much credit is due to the work of the museum
for creating a fascinating display that will no doubt be of great public
interest. Unfortunately, the current display fails to conserve the features that made the
original discovery of unique importance. The four isolated footprints
displayed are orientated
parallel to each other and provide little indication that they once belonged to a
trackway. Perhaps at some point in the future the footprints will be
realigned into a trackway and some of those missing parts reconstructed to restore
the features most important to the original discovery.

Left: One of many incredible dinosaur trackways
discovered at Ardley Quarry in Oxfordshire. The position and spacing
between the footprints of this principle
set, thought to belong to a Megalosaurus, provided a unique insight into the
way these ancient reptiles walked and ran. Despite its
significance much of the
trackway was inadequately conserved and eventually destroyed. Original
in situ photos
for reference:
high-res photo 1
high-res photo 2
high-res photo 3.Right: A small number of the dissected footprints
are displayed at the Oxfordshire Museum. Despite much credit being
due to the museum, the display conserves
little of what made this discovery important. Most
of the trackway is missing and what footprints are featured are
incorrectly orientated.

Left: One of the 'Megalosaurus' footprints
in situ at Ardley in 2002. The rain that day had
accumulated in the prints creating a scene reminiscent of Jurassic
Park!Right: The same(?) footprint displayed at the
Oxfordshire Museum in 2010 - it appears to resemble the footprint
featured (left).

In our view the Ardley case illustrates a tremendous loss of
scientific evidence despite the details of the original trackway
being recorded. Fortunately the remaining trackways are now
protected to avoid further unnecessary loss.

Preparation practices

Having collected the specimen the next stage concerns its
preparation to reveal the evidence available and ensure its
long-term stability/durability. As above, decisions here can greatly
affect the scientific value of the specimen - too little preparation
and the information available may remain concealed; too much
preparation and the specimen may become overly vulnerable to
accidental damage. The following section discusses some of the
common 'enhancements' and 'adaptions' that can cause irreversible
damage, and are therefore best avoided.

Varnishing: Many collectors have considered or
have applied a varnish/lacquer to fossils at some point in the
past, often in the early stages of collecting. Varnishing offers
some benefits including strengthening fragile specimens and
'enhancing' the specimen's appearance, the latter of which is a
matter of personal preference. Without easy access to superior
alternatives, e.g. Paraloid B72, a varnish/lacquer can appear a good
substitute.

Unfortunately, the application of varnish has a number of
drawbacks - it obscures surface details, creates an artificial
appearance, restricts future preparation and repairs, is difficult
to remove without damaging the specimen and limits the appeal to
fellow collectors.

Left: A brachiopod from Woodeaton Quarry
(Oxfordshire). In its natural state the specimen and surrounding
matrix allow every detail to be clearly visible.Right: The same specimen with a clear varnish
applied to the surface. Many of the subtle surface textures have been
obscured, along with much of the shell.

Generally speaking a surface coating is unnecessary, if handled with
care and stored in a safe, dry place most fossils will be stable in the
long-term. Exceptions include some specimens preserved as iron pyrite for
example, which are susceptible to oxidisation. When pyrite (FeS) oxidises
the reaction produces sulphuric acid (H2SO4) as a by-product. This acid then
reacts with a much greater variety of materials, eventually dissolving the
entire fossil. A transparent lacquer in this instance may delay/slow the
rate of decay. An alternative and recommended
technique for unstable pyrite specimens is to store them in a sealed bag
accompanied by a sachet of silica gel; experienced collectors may also use
ammonia to halt the decay.

Polishing: A practice to generally avoid is
surface polishing, usually associated with mass
market fossils for sale, in particular cephalopod shells, e.g.
ammonites, nautili and orthocones. Polishing typically seeks to
increase the visual contrast of surface structures, or reveal the internal fabric of the fossil
- for example the spiralling
chambers of an ammonite shell. Some claim polishing restores the
fossil to how it might once have looked, but this is rarely the
case. Polishing is irreversible and the process removes the fossil's outer surface, losing much of the specimen
and any associated environmental/biological evidence in the process.

Left: A collection
of polished clypeasteroid 'Sand dollar' echinoids from Madagascar.
Polishing has removed much of the finer details at the surface of
the test.Right: A well presented Menopygus nodoti
echinoid displaying the intricate surface tubercles to which the
spines attached in life.

In the example above the surface of the echinoid's shell is beautiful
and complex, the subtle details of this patternation are often
key to identifying the species, and also understanding how it lived.
The pores, tubercles and aureoles record the complex array of spines
and other body parts that were present on the outer surface of the
echinoid in life. Polishing irreversibly obliterates this information.

Left: This mammoth tooth may feature beautiful internal
structures, but polishing has removed much of the fossil and with it much
of its scientific value.Right: For comparison, a mammoth tooth from Colne Quarry. The specimen has been carefully cleaned and strengthened with a dilute concentration of
Paraloid B72 (5%), without which the tooth would likely break. Preparation
in this way conserves the intricacies of the tooth and therefore the scientific value.

Arguably there are some benefits to polishing certain fossils, for
example fossil bearing limestone quarried for the manufacture of kitchen
surfaces and other household items. Similarly there's no significant loss
caused by polishing some fossils for display, e.g. exceptionally abundant
Moroccan orthocone nautiloids, as doing so provides some aesthetic and
educational benefits and their widespread distribution as ornamental pieces
helps raise public familiarity with fossils. Amber containing
fossilised organisms is also an exception, without which the internal
fossils would be obscured. However a distinction should be made between
polishing common fossils and applying the same technique to fossils of
greater scientific value. As a general rule it's best to avoid polishing
specimens that can be conserved and presented in their natural state.

Slicing: Among the most
controversial practices is the slicing of prehistoric evidence to
reveal the internal structure, often undertaken in conjunction with
polishing. There are instances where slicing can be beneficial i.e.
the loss is outweighed by the aesthetic and/or educational benefits.
For example, a heavily worn, common ammonite shell where the surface
is beyond recognition and offers limited value in its present state
- slicing in this instance might reveal the internal mineral-filled
chambers of the shell. Similarly a specimen may be sacrificed within a laboratory in order to expand our
understanding of a particular species, e.g. slicing dinosaur bone in
an attempt to inform the ongoing hot-blooded vs cold-blooded debate.
Similarly some fossils, e.g. foraminifera, are routinely sliced by
academic palaeontologists, as doing so is the only effective means of identifying
them.

In practice, slicing isn't confined to the examples above. The commercial
market in particular is awash with specimens that were arguably of greater value in their
complete state. For example, it's not uncommon to find associated vertebrate
bones sliced and sold as separate specimens. An association of bones may
require many more hours to prepare scientifically than to cross-section for
sale. Similarly, the sliced parts may collectively generate more revenue than
the original complete specimen, especially if the original specimen's
appearance narrows its appeal.

Left: This sliced
'dinosaur leg bone' for sale online, once belonged to a
more complete specimen that was destroyed in the process.Right: This common ammonite
is typical of the sliced and polished fossils available for sale around the
world. Its preparation in this way is less controversial.

As a general guide it's best to avoid slicing in the majority of
instances. Often the outcome of slicing is disappointing as the internal
structure is neither aesthetically pleasing nor educational, resulting in
an unappealing specimen. A fossil is rarely of greater scientific value
when sliced than in its complete state.

Modification: Most collectors have ‘improved’
specimens at least slightly, be it filling in cracks or painting
over a small chip. On a small scale this is usually quite harmless
and can help retain the visual appeal of a specimen without altering
the anatomical information. Opposite extremes are widely seen in the
commercial market, where composite specimens are abound, and fossils
are routinely carved to enhance their appearance. There is a large
grey area between the extremes though, and it's often hard to know
when you've ‘gone too far’. For example, it's common to see the
centre of an ammonite carved in. This is a ‘constructive’
modification where no actual harm has been done, but it does serve
to confuse the anatomical story – many academic palaeontologists
have been fooled
by an artfully improved fossil. A more controversial practise is
destructive modification, such as the removal of ‘unsightly’ outer
whorls on ammonites, which are often crushed. This constitutes real
loss of information and should only be acceptable for the very
commonest fossils.

Left: An extreme example of a modified
fossil. Isolated fragments of Moroccan mosasaur(s) have been
combined to appear to be a single specimen.Right: The fossils of the Brazilian Santana
Formation provide many classic examples of 'improved' fossils. Here
sections of two unrelated fish have been
combined, and a dorsal fin carved in to give the impression of a
single fish.

Left: At first glance this chalk fish appears to be
an exemplary prep job, until that is you notice the scales are absent -
seemingly removed by the Victorian
preparator in an example of destructive modification. It appears
the desire to reach the bones took precedent over conserving
the full specimen.Right: An equivalent example where the scales have
been respectfully retained. The scales are typically very fragile
and require great skill and patience to prepare.

Over preparation: For certain fossils (typically
spiny ones), it's tempting to remove large amounts of matrix to achieve a spectacular display piece. Most people are familiar
with Moroccan trilobites, which can be wildly ornamented. As well as looking stunning, the preparator’s skill has
also exposed the full anatomy of the fossil; however, the downside
is the extreme fragility of these specimens which all seem destined
to be damaged. For abundant forms like the Moroccan trilobites this is
probably a justified risk, but for rarer fossils this should be
avoided. The echinoid figured below is an example of what typically
befalls an over prepared specimen at some point. An example is also
figured in the introduction at the top of the page, where a specimen
prepared by one of the authors will need a plaster backing if it's
going to survive undamaged in the future.

Left: This 19th century illustration captures this
scarce and stunning, but tragically over-prepared Hirudocidaris. Sadly this
example has since been poorly
stored and handled at some stage in its history.Right: The same specimen in its present state of
disrepair, with much of the specimen lost. Thankfully it's now in
appropriate storage at the Booth Museum
in Brighton where no further harm should come to it. A more
conservative prep job would have improved this specimen’s chances of
surviving the centuries.

Storage practices

Safe storage: Of course, no matter how
conscientious the collection and preparation, all can be lost if the
method of storage fails to protect the specimen from damage in the
long-term. Finding a balance between enjoying a specimen and
limiting the risk of damage from movement and handling can be
difficult. Many fossils are susceptible to breakage, especially if,
as highlighted above, the matrix has been significantly reduced to
expose the fossil. In the example below-left it's clear that
suitable storage arrangements have been neglected, consequently
areas of the echinoid's test are now absent presumed knocked off.
For comparison the example on the right (stored at the Natural
History Museum in London) illustrates how even specimens from very
old collections can be protected.

Recording information: Labelling of specimens is critical if they're to retain their scientific
value. This should include location as a minimum, and ideally details of the
source horizon / formation such as is known. For evidently significant
specimens collected in unfamiliar locations, information should be quickly
sought on the local stratigraphy so that the specimens stratigraphic context
can be established whilst the information is fresh in the collector’s
mind. It's less important to display the identification of a specimen, as
this is subjective and names are subject to change. It's usually possible to
attach a specimen number to even a small specimen, which can then be related
back to a collection catalogue. Ideally a full description label can be
attached to the reverse side of the matrix, but this is often impractical.

Left: Specimen drawers at the Natural History Museum
in London. The fossils are arranged into draws by rock formation /
age and then genus. There are no
strict guidelines for how a private collection should be arranged,
rather it simply needs to be organised to provide easy access to the
specimens.Right: Within the draws specimens are labelled and
stored within suitably sized cardboard trays to prevent them coming
in contact with one another.

Left: A collection of ammonites for sale in a shop
window. The absence of any matrix or recorded information, e.g. local origin,
rock formation, species etc.
makes identifying them more complicated. It's generally good practice to
accompany your finds with as much information about them as possible
read
more.Right: A drawer of chalk fish at the
Booth Museum, each specimen accompanied by an information slip
documenting their specimen number, and in
some examples the source location, species etc.

Further information and support

If you have a comment or question please contact us using the link
at the top of the screen. We're happy to provide independent advice
on a range of subjects including conservation, preparation and the
protection of locations/fossils of scientific value. If we're unable
to answer your questions we have a network of academic and
professional contacts who will be able to help you further.

Join us on a fossil hunt

Left: A birthday party with
a twist - fossil hunting at
Peacehaven.
Right: A family hold their prized ammonite at Beachy Head.

Discovering Fossils guided fossil hunts reveal evidence of life that existed
millions of years ago. Whether it's your first time fossil hunting or you're
looking to expand your subject knowledge, our fossil hunts provide an
enjoyable and educational experience for all. To find out more
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Special thanks to Professor Norman MacLeod at the Natural History Museum for proof reading the article.

Safety notice: Fossil hunting can at times pose a risk to personal safety, in particular within environments close to the coast, cliffs
or in quarries and when using the tools and equipment illustrated. Discovering Fossils provides a free resource to inform you about
this fascinating subject and does not accept any liability for decisions made using this information. We recommend all individuals
abide by the fossil hunting guidelines available by clicking on the icon at the top of the page.